M16 Rifle and M4 Carbine: Time For a Change

For those of you who may have been on another planet for the past three or four years, our troops in Iraq and Afghanistan are having serious reliability issues with the M16 rifle and M4 Carbine, especially the latter. The basic problems with the M16 and M4 are nothing new. M16 reliability issues date to the mid-1960s and more recently, a study of the M4A1 conducted by the Special Operations Command in 2000 stated that the M4A1 was “fundamentally flawed” for a number of reasons.

The M4/M4A1 Carbine has also turned out to be a poor “people stopper” when used with standard M855 ball ammunition. This is less of an issue if one is carrying an M16, but most troops in the “Sand Box” are equipped with M4 or M4A1 Carbines. The difference between the M4 and the M4A1 is that…
the M4A1 has a flat top upper receiver, while the M4 does not. Most Special Forces have the M4A1 with a MIL-STD-1913 rail upper receiver and handguard adapter, while the M4 has an M16A2 type upper receiver. Most “Big Army” troops are equipped with the basic M4. The causes of reliability issues and how they can be resolved are the subjects of this essay.

There have been repeated calls for a new small arms family to replace the M16/M4, notably the XM8 program that died a deserved death at the hands of Congress because in the words of an Infantry Colonel acquaintance at Fort Benning, Georgia, the XM8 did nothing significantly better than the small arms it was intended to replace. The Mark 16 SCAR (a.k.a. FN MK16 a.k.a. FN SCAR-Light a.k.a. FN SCAR-L) has also been proposed as a replacement for the M16/M4 family, but like the XM8, the Mark 16 really doesn’t do anything much better than the weapons it would replace. The Mark 16 was developed for Special Operations, because the M4s reliability issues seemed beyond the capability of the Army and the contractor to rectify. The Mark 16 was never intended as a replacement for the current family of small arms, nor should it be, particularly when the M16/M4 reliability and lethality issues can be rectified without acquiring an entirely new family of small arms. All that is necessary is what the military calls a “product improvement program,” or “PIP” that upgrades the current weapons.

My first encounter with the M16 came almost 40 years ago in Vietnam. By the time I reached Vietnam, I had been in the Army for five years and had heard the horror stories regarding the M16’s reliability – or lack thereof. It thus came as no surprise when I signed for my M16A1 at Headquarters, Military Assistance Command, Vietnam (MACV) prior to going “up country,” the arms room sergeant told me not to bet the farm on it. I didn’t and acquired a reliable M1A1 Thompson Submachine Gun that I used throughout my tour, while my issue M16A1 sat in a wall locker, unfired. It can thus be seen that the M16’s reliability issues are nothing new. The Army’s solution to early M16 lack of reliability was intensive maintenance – far more than was required for previous rifles like the M1 and M14. M14s, by the way, are being withdrawn from storage and reissued by the thousands; many to Special Forces in a modified version designated the Mark 14, Mod 0 Enhanced Battle Rifle. In fact, an entire generation of American service personnel has come to accept the M16 family’s intensive and time consuming maintenance as the norm when nothing could be further from the truth.

The M16/M4 reliability issue begins with the weapon’s gas system, which in the words of another journalist, “vomits into its own mouth.” The Ljungman-type direct impingement gas system is simple and lightweight, but it blows hot gases, carbon fouling and unburned powder particles directly back into the weapon’s receiver. Not only does this require intensive maintenance, but heavy lubrication to keep the fouling soft and the rifle operating. In the hostile Iraq environment where dust the consistency of talcum powder gets into everything, the lubricant becomes a “dust magnet,” causing frequent stoppages (jams) – just what you need in a firefight! Both M16 and M4 weapons have this problem. Anyone who has ever cleaned an M16 or M4 remembers the caked on carbon fouling that must literally be scraped off the internal components of the bolt carrier assembly.

In the case of the M4, the gas problem is made even worse because the gas port has been moved back to within six inches or so of the upper receiver, meaning that gases entering the receiver are hotter and under higher pressure than those of the longer barreled M16. The hotter, higher pressure gases not only raise the operating temperature in the forward area of the upper receiver, but also in the magazine well area. Just as bad, the gases cause accelerated gas port erosion, further raising pressures and dumping even more hot gases into the upper receiver. Higher pressures cause timing issues, which results in the weapon unlocking before pressures in the barrel have dropped and while cartridge cases are still clinging to the chamber wall, blowing extractors, breaking bolts and stripping locking lugs. A partial solution to this issue is to replace the direct impingement gas system with a gas piston and operating rod system.

There are a number of gas pistol/operating rod (Piston/op rod) systems available that for the most part alleviate the gas pressure and fouling issues. One such system is Heckler & Koch’s HK416 replacement upper receiver that is already in extensive use by Special Forces. There are two basic problems with the HK416 conversion, however. First, “Big Army” cannot get them and second, H&K will not sell them commercially, so any police officer or civilian who wants one can’t get one. There are alternatives, though.

One of the best is Patriot Ordnance Factory’s P415, available as a conversion upper receiver or complete rifle. The P415 features a full length MIL-STD-1913 free float tube with rails spaced 90 degrees apart, and even better incorporates a simple and effective piston/op rod system that can quickly be disassembled for inspection or maintenance. The best feature of the P415, though, is that it requires no lubrication whatsoever. The P415 runs dry because the upper receiver interior is plated with silicon nickel and the bolt and all working components are hard chromed. The silicon nickel and hard chrome are self-lubricating and what little fouling that does find its way into the receiver can simply be wiped off with a dry rag.

I have fired the P415 extensively and if I were to deploy to Iraq or Afghanistan, it would be my weapon of choice and if I could have only one AR-type rifle, it would be a P415. The P415 is what I carry when I am on duty at the local police department, where I am a reserve officer. As one can imagine, though, the P415 is relatively expensive, but if you want what is arguably the most reliable AR-type carbine on the planet, the P415 is the way to go. In documented testing, P415s have fired over 20,000 rounds without cleaning or lubrication other than wiping fouling off with a dry rag, a record that is unbeatable by any other manufacturer’s product at any price. My personal P415 has never been lubricated other than a light spray of TW-25B dry PTFE on the internal components after wiping them off with a dry rag. The TW-25B is a dry lubricant and so doesn’t attract dust.

For those on a budget or who simply don’t wish to go the expense of purchasing a complete piston/op rod upper, there is the Ares Defense GSR-35 “Black Lighting” piston/op rod conversion. The GSR-35 simply replaces the M4 gas tube and bolt carrier with a piston/op rod unit and a bolt carrier configured for use with an op rod. The conversion takes only a few minutes using simple tools and should be well within the capabilities of anyone having a good working knowledge of the AR-type system. I was able to install a GSR-35 onto an M-4 type carbine in less than 15 minutes and the system has functioned with total reliability ever since. Like the other piston/op rod systems, once the GSR-35 is installed, fouling issues are resolved. The only down side to the GSR-35 is that it is presently available only for short handguard M4-type carbines, although versions for rifles with full and intermediate length handguards are under development.

Any of the systems described above will greatly reduce the need for heavy lubrication and intensive maintenance associated with the M16/M4 family, although the P415 is the only one that eliminates conventional lubrication altogether. The bottom line with respect to M16/M4 family is that once the direct impingement gas system has been replaced, intensive maintenance is no longer necessary. This isn’t to say that the carbine no longer requires cleaning – just no longer on a daily basis as is currently the case. Any of the three systems described above can be installed on existing weapons as a product improvement with no need to buy an entirely new small arms family.

So there you have it! Our troops are burdened with basic weapons that are subject to chronic reliability issues in the “sandbox,” but the fixes are simple, available now and relatively inexpensive when compared to buying an entirely new small arms family. In closing, we have to wonder why the Army hasn’t done something to address these well known and extensively documented M16/M4 reliability issues. The solutions already exist and we definitely DO NOT need a new family of small arms. Civilians don’t have to use “issued” carbines, however. Although H&K will not sell its HK416 commercially, even to law enforcement, anyone can buy a P415 or GSR-35 and upgrade their AR type rifle or carbine. Either is well worth the investment.

About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

4 comments

love how the author says the XM8 and the SCAR didn’t do anything better than the M4/M16, when they were over 3 times as reliable in the testing compared to the Stoner designs.

and then the author goes on to just suggest a short-stroke piston upper into the M4/M16. yeah, because we all know shoe-horning in a piston to a gun that wasn’t designed for it is a great idea….why would the author want the POF415 so badly in the sandbox, but not the SCAR or XM8 (both WAY better than any M4/M16 style rifle)?

this is just a shill for POF trying to drum up sales, nothing more. the fact is the M4/M16 is outdated and not that great of a design, putting a short stroke piston upper onto it is just a band aid, you need a new rifle that is designed FROM THE GROUND UP to be a piston rifle. SIG 550 series is a great solution, as is the SCAR, ACR or XM8. all of those are brilliant and superbly reliable modern piston designs that run circles around the ancient Stoner platforms.

don’t band-aid the problem with a piston upper for the M4, FIX the problem with a whole new rifle. i mean for god’s sake there are borderline third world countries now using rifles like the FN SCAR, Beretta ARX and SIG 550 series. fucking MEXICO just ordered a bunch of Beretta ARX-160s for their military and national police. MEXICO is way ahead of us in small arms technology, that is fucking pathetic.

ditch the whole Stoner family. piston or not, the rifles are old and need replaced with 21st century modular designs. also get us off the 5.56 platform and onto 6.8SPC. the ARX-160 is a great gun because it is totally tool-less and you can swap calibers in about 1 minute, you could go from 5.56 to 6.8SPC while your buddies covered you, for example. and yet the ARX will be another great futuristic rifle denied by the US government due to red tape and budget complaints.

IMO we need to be running the SCAR or ARX, but i’d also be fine with SIG 550 series guns. i personally have fired the civilian version of the Beretta ARX and it is an amazing rifle, i’d call it the best fighting rifle in the world right now, it’s a totally perfect 21st century design, with the SCAR coming up in 2nd place, then the SIG 550s and then maybe the ACR in last place. All are leagues ahead of the M4/M16.

if our soldiers are so fucking stupid that they can’t learn new weapon platforms, i weep for our future. they shouldn’t be in the military at all if they’d have trouble learning a new rifle.

best rifle of the future would be a ARX-160 or SCAR in 6.8SPC, the ACR sadly had its chance and failed due to being poorly handled by Remington and Bushmaster. the XM8, despite being the best performing rifle at recent military tests, was denied due to red tape politics. the SCAR is actually being fielded by US Army Rangers and some other groups in small numbers, so is the HK416, word of mouth is the guys who are using the SCAR really love it…HK416 seems to have problems though in the sandbox, again, because it is a Stoner platform that is just band-aided with a piston, not a rifle built from the ground up as a piston rifle.

but IMO we need the Beretta ARX-160 in 6.8 SPC as the rifle of the future and ditch the old M9 for a Glock 17, S&W M&P or if they want to keep in line with Beretta, the PX4 Storm is a fine pistol as well.

just imagine if we never upgraded from the Springfield 1903, lol. or post-WW2 never upgraded from the Garand. fact is america used to be the technological military, now we’re being overshadowed by many other countries…look at some of the new small arms being used by Russia and China, makes us look like a joke in comparison.